Flowmeters are used to measure liquid flow rates or volumes. A variety of devices have been employed, including weight cells, rotameters, spinning disk or spinning rotor sensors, capacitive sensors, pressure sensors and Faraday effect sensors. References describing such devices include U.S. Pat. Nos. 4,008,609, 4,099,412, 4,118,981, 4,145,924, 4,434,667, 4,683,748, 4,732,160, 4,881,413, 4,899,592, 5,046,510, 5,062,304, 5,078,012, 5,176,148, 5,207,105, 5,325,728, 5,327,787, 5,495,854, 5,708,212, 6,237,424 B1 and 6,463,807 B1.